The present invention generally relates to imagers having an array of light-sensitive imaging elements. More particularly, the present invention relates to imagers with such an array positioned close to an edge of an underlying substrate relative to the other edges of the array and substrate.
For some imaging applications, the location of an active area of an imaging array relative to what is being imaged is important. For example, in medical applications such as mammography, current U.S. federal regulations state that the distance between the chest wall of the patient and the active imaging area must be no more than 6 mm, while German regulations currently require no more than 4 mm. At the same time, companies manufacturing such imaging equipment are concerned about the useful life of the imagers. Such spacing limitations can create physical limitations for components of the imager, affecting its useful life.
For example, a scintillator used to emit visible light in response to radiation and placed over a light-sensitive imaging array is sealed beneath a cover to prevent damage to the scintillator from such things as moisture in the air. However, due to the placement of the array and the space taken by the external housing, there is insufficient area for a proper sealant thickness. While it is possible to fit a thin line of sealant, such a thin line may be insufficient to prevent diffusion of moisture for any appreciable amount of time, since the time for degradation of the sealant is related to its width.
The present invention provides an imager having a substrate, an array of light-sensitive imaging elements on the substrate, a scintillator over the array, and a cover over the scintillator sealed to the substrate around a periphery of the cover. At least one edge of the array is situated closer to a respective edge of the substrate relative to other edges of the array and substrate. The imager also includes an end cap sealed to and covering the edge of the cover, the edge of the substrate, and a portion of each of the cover and substrate inward from their respective edges.
The present invention also provides a method of sealing an imager. The method includes sealing a cover for the scintillator to the substrate around a periphery of the cover, and sealing the edge of the cover, the edge of the substrate, and a portion of each of the cover and substrate inward from their respective edges with an end cap.